Air conditioning systems involve the correlation of air distribution circuits, heating and cooling storage and fluid transfer circuits, and energy therefor; all for maintaining a temperature range within one or more zones of a building complex. Energy is normally consumed by the expenditure of resources and supplemented by "solar insolation" for applied heating and by "terrestrial re-radiation" for applied cooling. It is a "water source" system with which this invention is concerned, a system that is adaptable to the storage of heated and chilled fluids and the distribution of the same to various building zones according to demand. Maximum reliance upon solar heating and terrestrial re-radiation is a primary object of this invention, with a minimum expenditure of externally supplied energy.
Solar heating and cooling by re-radiation are not totally sufficient in most instances for adequate conditioning and it is contemplated that an outside energy source such as a fuel or electrical power or the like be relied upon as circumstances require. Efficiencies are realized with the use of insulation, re-circulation and cleaning of the conditioned air, and by the exchange and/or sharing of heating and cooling requirements of separately conditioned zones within the building complex. Nevertheless, heating and cooling systems can be wasteful in expending energy for their operation and it is a general object of this invention, therefore, to maximize the availability of solar isolation and to conserve and reclaim energy in an air conditioning system and especially in a water source or fluid system. With the present invention, the available heat content of separately stored fluid masses is maximized for both heating and cooling.
The consumption of fuel and electrical energy in the operation of a building complex goes to provide relatively low heat end uses, such as domestic hot water heating in the range of 125.degree.-140.degree. F. and space heating by forced convection in the range of 95.degree.-110.degree. F. The burning of a high quality fuel at relatively high combustion temperatures such as 1800.degree. F. is fundamentally wasteful when its heat is transferred to the said low temperature uses. For example, the use of direct combustion of fuel to heat water requires approximately eight times as much fuel as that required by a Rankine cycle prime mover doing the same work, even when discounting the usual combustion process losses; i.e., domestic water heaters have a maximum heat transfer efficiency of about 70%. In other words, work as contrasted with heat is intrisically the more valuable form of energy, and the measurable value of a fuel is stated as "the extent to which its energy content can be converted to work", and this quality is the "thermodynamic availability" of the fuel. The measurement of efficiency at the point of consumption is based upon a comparison of thermodynamic availability actually consumed. For instance, in the operation of an on-site boiler heated with fossil fuel, the ratio of the thermodynamic availability required to the thermodynamic availability consumed is estimated for space heating to be about 0.03 or less, and for domestic water heating to be about 0.10 or less. For electrically driven refrigeration the said ratio is about 0.12 or less. With the present invention, incident solar energy is made available to do work by operating a heat engine, preferably a Rankine cycle prime mover, by which work is irreversibly extracted and the remaining thermal energy staged in a stratified storage at temperatures conducive to the efficient operation for each process involved; namely space heating, and domestic water heating, all to the end that loss of thermodynamic availability is minimized. It is an object therefore to trade off the installation costs making available solar energy by insolation against reduced fuel consumption, all without sacrificing conventional performance.
In air conditioning systems of the type under consideration a portion of the energy is lost from condensors, evaporators and compressors, to become waste heat, and it is an object to reclaim this heat as such and/or to contain it within the system as energy. To this end a stratified thermal mass is provided for the storage of solar heat used in the operation of one or more water source heat exchangers and/or induction type exchangers, and to operate a Rankine cycle prime mover for motivating vapor compression refrigeration used to chill a water source and with one of its closed circuit condensor systems combined with heating coils of the air conditioning system.
Vapor compression refrigeration requires power for its operation and the aforementioned Rankine cycle prime mover is available to serve this power when sufficient solar energy is available, and to this end the said prime mover is coupled to the mechanical refrigeration for its motivation, it being an object to claim solar energy for system use. In the event that solar energy is insufficient, an externally powered motor-generator is also coupled to the mechanical refrigeration for its motivation with or without solar energy assistance. And, in the event that solar energy is available when motivation of mechanical refrigeration is not required, the said motor-generator is uncoupled from the mechanical refrigeration and remains coupled to the Rankine cycle prime mover for the generation of power into the electrical energy source system to be used elsewhere or in operating the system.
It is an object of this invention to advantageously employ heat concentrating solar collectors, preferably of the panel-tube type, and the storage of energy therefrom for subsequent heat exchange and to operate a Rankine cycle prime mover for the motivation of mechanical vapor compression refrigeration. With this invention, the collection of solar energy to be used through heat exchange or by the Rankine cycle prime mover is shared in the water source system by transmission through the stratified storage where the moderate heat range of fluid stored for zonal heat exchange is separated from the high heat range of fluid stored for prime mover operation.
It is also an object of this invention to reduce the size requirement of refrigeration machinery and prime mover therefor by drawing upon storage of chilled fluid during periods of peak cooling load demand. With the present invention, waste heat normally rejected to atmosphere by Rankine cycle prime mover systems is advantageously utilized so that overall system efficiency is significantly improved. Further, it is an object to realize efficiency by claiming and/or reclaiming power, and with the present invention excess power derived by solar insolation is stored and thereby conserved for subsequent extraction on demand of the system.
It is also an object of this invention to advantageously employ terrestrial re-radiation of heat from the system, with the storage of water chilled thereby in storage separate from the aforesaid stratified heat storage.
It is another object of this invention to advantageously employ a low heat range water storage for pre-heating a domestic hot water system of the building complex, to be supplemented by fuel or an outside energy source as circumstances require. The high and moderate heat range levels are supplemented and/or maintained for efficient operation of the system by means of controlled heater means within the stratified sections of the thermal storage and operated from a fuel or outside energy source.